238 Lang.— Studies in the Morphology and 
stimulated to active growth. While the buds are part of the primary con- 
struction of the plant, the vascular connexions of the branch with the main 
shoot have to be established in more or less mature tissues ; this accounts 
for the variety in detail found in this respect. 
The chief vascular supply of the branch is derived from a development 
of xylem adaxially to the subtending leaf-trace. This xylem is strictly 
comparable to the adaxial xylem referred to under (5). The vascular 
supply to the branch may arise from the subtending leaf-trace when the 
latter has already separated from the stele, or it may arise lower down in 
the axil of the leaf-trace. A more or less extensive vascular connexion 
may also be present between the branch and the stele of the stem, in the 
neighbourhood of the leaf-gap. 
The vascular supply to the branch becomes organized into a medullated 
stele. This is sometimes small, but in other cases is much larger than the 
stele of the parent rhizome ; in the latter cases the stele of the branch 
diminishes in diameter above its base. The stele of the branch at first 
shows a gap opposite to the subtending leaf-trace, so that the latter appears 
as if it were derived from the branch stele. The stele of the branch, 
which shows a general resemblance to that of a plant developed from an 
mbryo, may acquire an internal endoderm is ; the origin of the pith, however, 
is below and independent of this. 
Concluding Remarks. 
As stated at the beginning of this paper, any full discussion of con- 
clusions will be deferred until the corresponding facts for other Ophio- 
glossaceae have been described. A brief reference to the conclusions 
towards which this study of Botrychium Lunaria appears to point is, however, 
necessary. 
The re-examination of B. Lunaria has revealed a number of features in 
the anatomy which considerably modify our general conception of the 
construction of the plant. The most striking of these is the regular presence 
of a vestigial axillary bud in relation to every leaf, and the reference of the 
occasional branching of the rhizome to the active growth of one or more of 
these. This justifies us in regarding B. Lunaria as a potentially branched 
plant, the buds being part of the primary construction of the plant and not 
adventitious. This feature at once suggests comparison with Helmintho- 
stachys , and with the Hymenophyllaceae and Zygopterideae, 1 and it is 
with these latter groups and the Osmundaceae that comparisons would most 
naturally be made on the ground of general anatomy. 
A distinction between inner (or centripetal) and outer (or centrifugal) 
primary xylem can be traced from the basal region throughout the plant. 
I am inclined to attach importance to this, especially in the light of the 
1 Cf. Scott, Annals of Botany, vol. xxvi, p. 59. 
